Interlock system for metal enclosed switchgear having a fuse drawer and sliding panels

ABSTRACT

A metallic housing encloses high voltage switchgear including a horizontally slidable fuse drawer having a switch pivoted on each side with vertically slidable access panels for the switches. An interlocking system prevents: opening of the fuse drawer and removal of the sliding panels unless both switches are open, closure of either of the switches with the fuse drawer open and replacing the panels in their fully closed positions after the fuse drawer is closed.

United States Patent 1 1 3,573,560

[72] Inventor Edward J- Rogers [56] References Cited Chimflm UNITEDSTATES PATENTS [21] P 1,402,123 1/1922 Wadsworth 337/8 [22] 1969 3 309576 3/1967 Sims 317/99 45 Patented Apr. 6, 1971 3 339 118 8/1967 name317/114 [73] Assignee s & C Electric Company Chicago, Ill. PrimaryExaminer-E. A. Goldberg Assistant Examiner-Gerald P. TolinAtt0rney--Robert R. Lockwood [54] INTERLOCK SYSTEM FOR METAL ENCLOSEDSWITCHGEAR HAVING A FUSE DRAWER AND G ABSTRACT: A metallic housingencloses high voltage mg switchgear including a horizontally slidablefuse drawer hav- [52] US. Cl 317/114, ing a switch pivoted on each sidewith vertically slidable ac- 200/50 cess panels for the switches. Aninterlocking system prevents: [51] Int. Cl H02b 1/04, opening of thefuse drawer and removal of the sliding panels l-lOlh 9/20 unless bothswitches are open, closure of either of the switches [50] Field ofSearch ZOO/50.15, with the fuse drawer open and replacing the panels intheir fully closed positions after the fuse drawer is closed.

Patented April 6, 1971 4 Sheets-Sheet 1 FIG. I

- v V Ill v Patented April 6, 1971 4 Sheets-Sheet 8 Patented A ril 6,1971 4 Sheets-Sheet 5 Patented April 6, 1971 4 Sheets-Sheet 4 INTERLOCKSYSTEM FOR METAL ENCLOSED SWITCIIGEAR HAVING A FUSE DRAWER AND SLIDINGPANELS This invention is an improvement over the disclosure of Harner etal., U.S. Pat. No. 3,339,118, issued Aug. 29, 1967 and is adapted foruse with the structure disclosed in a copending Emmett R. Beebeapplication.

In the application above referred to a fuse drawer is horizontallyslidable in a metallic housing and has loop feeder switches on eitherside for connecting fuses which supply a load circuit for energizationto either side of the loop circuit. Vertically slidable metallic panelsoverlie the switches and, when removed, provide access to them forinspection and servicing.

Among the objects of this invention are: To prevent opening of the fusedrawer if either of the switches is closed; to permit removal of eitherof the sliding panels only when both switches are open; to preventclosure of either of the switches when the fuse drawer is open; and toprevent replacement of either of the sliding panels to its fully-closedclosed position except when the fuse drawer is open.

According to this invention a metallic housing is provided in which afuse drawer is horizontally slidable. On either side of the fuse drawerthere is a loop feeder switch for connecting fuses on the fuse drawer toeither or both sides of a loop feeder circuit, the fuses being connectedto a load circuit. To permit access to the switches for inspection andservicing vertically slidable metallic panels are provided on oppositesides of a panel of the fuse drawer on which the fuses are mounted. Amanual switch operator for each switch includes a pivoted member that ismoved between closed and open positions. The fuse drawer has upper andlower notched lock plates along each side with the notches arranged toreceive upper and lower pivoted latch plates to lock the fuse drawerclosed. The latch plates along each side are connected for conjointpivotal movement. Each upper latch plate is connected to the respectivepivoted member in such manner that the latch plates hold the fuse drawerclosed when the switches are closed and disengage the lock plates whenthe switches are open to permit opening of the fuse drawer. Endwiseslidable locking pins are arranged to overlie inwardly extending flangesof the slidable panels along their lower edges to prevent removalthereof. The locking pins are moved between panel locked and unlockedpositions by panel lock levers on a pivoted shaft which is moved betweenpanel-locked and panel-unlocked positions by detents on the fuse drawer.Extensions of the panel lock levers function as detents to engage thelower latch plates and prevent closure of the switches when the fusedrawer is open. If the fuse drawer is closed with the panels removed,the locking pins are moved to their panel locked positions and thusprevent downward movement of the panels to their fully-closed positions.

In the drawings:

FIG. 1 is a perspective view of metal-enclosed switchgear in which theinterlocking mechanism of this invention is embodied, the metalenclosure being shown in outline by broken lines in order to permitillustration of the switchgear comprising fuses and switches within theenclosure;

FIG. 2 is a perspective view, at a reduced scale, of the metallichousing shown in FIG. 1, the view being taken looking generally from therear;

FIG. 3 is a horizontal view looking downwardly underneath the top panelof the metal enclosure shown in FIG. 1 and illustrates, somewhatdiagrammatically, the arrangement of the switches and the interlockmechanism;

FIG. 4 is a view in front elevation of the interlocking mechanism shownin FIG. 3, the illustration here also being somewhat diagrammatic incharacter;

FIG. 5 is a vertical sectional view at an enlarged scale showing aportion of the fuse drawer and how the detents thereon are arranged topivot a shaft which controls interlocks for the sliding panels;

FIG. 6 is a view, at an enlarged scale, taken generally along line 6-6of FIG. 4;

FIG. 7 is a view in elevation taken generally along line 7 7 of FIG. 6;

FIG. 8 illustrates diagrammatically the circuit connections for thefuses and switches in the metal enclosure shown in FIGS. 1 and 2.

In FIGS. 1 and 2 the reference character 10 designates, generally, ametallic housing that is adapted to be mounted on a concrete pad and itconstitutes, generally, a support structure for electrical switchgearmounted therein. The metallic housing 10 has vertical sidewalls 11 andI2 and a slidable top panel 13 which is described in more detail in theBeebe application above referred to. Horizontally slidably mounted inthe metallic housing 10 is a fuse drawer that is indicated, generally,at 14 and is provided with a fuse drawer panel 15 which, in part, closesoff the front side of the metallic housing 10. Insulators 16 extendrearwardly from the fuse drawer panel 15 and fuses 17 extend endwisethereof having fuse ter minals 18 at their distal ends for insertion inplug-in contacts 19 that are carried by insulators 20 which extendforwardly from an inner rear panel 21. Cable terminators 22, FIG. 2, areprovided on the rear side of the panel 21 to permit connection to a loadcircuit.

As shown diagrammatically in FIG. 8 the ends of the fuses 17 mounted onthe insulators 16 are provided with laterally and inwardly extendingcontact anns 24 and 25 that are arranged, in the closed position of thefuse drawer 14, to have contact engagement with contact plates 26 and 27of loop feeder switches that are indicated, generally, at 28 and 29. Itwill be noted that the loop feeder switches 28 and 29 are located onopposite sides of the fuse drawer 14 and that switch blades 30 and 31extend from the contact plates 26 and 27 and are arranged to be pivotedthrough arc chutes 32 and 33 into engagement with stationary switchcontacts 34 and 35 on which the arc chutes 32 and 33 are mounted.Insulators 36 and 37 support the stationary switch contacts 34 and 35and are mounted on and extend forwardly from rear members 38 and 39 ofswitch support structures that are indicated, generally, at 40 and 41.It will be understood that the switch support structures 40 and 41 aresuitably mounted within the metallic housing 10 and therewith provide asupport structure for switchgear cable terminators 42 and 43, FIG. 2,which are located on the rear side of the panel 21 to provideconnections to the loop feeder circuit from the stationary switchcontacts 34 and 35.

Access for inspection and servicing of the loop feeder switches 28 and29 is provided through openings in the front of the metallic housing 10which are closed by vertically slidable metallic panels 44 and 45. Theirconstruction is described in more detail in the copending Beebeapplication above referred to. As will appear hereinafter provision ismade for preventing opening movement of the fuse drawer 14 when the loopfeeder switches 28 and 29 are closed. Also provision is made forpreventing removal of the slidable panels 44 and 45, except when thefuse drawer 14 has been withdrawn. Further, the panels 44 and 45 cannotbe removed except when the top panel 13 is moved rearwardly as shown inFIG. 1 to uncover their upper ends.

In FIG. 3 it will be observed that the switch blades 30 and 31 arearranged to be pivoted about vertical axes by arms 46 and 47 which areconnected by links 48 and 49 to arms 50 and 51 which are pivoted with asnap action by spring operators, generally indicated at 52 and 53, whichmay be constructed as disclosed in a copending Bernatt-Gelfandapplication. The spring operators 52 and 53 are operated manually onpivotal movement of tool receiving shafts 54 and 55. A suitable crank orwrench-type of tool can be attached to the upper ends of the shafts 54and 55 or suitable operating handles can be permanently secured thereto.As shown in FIG. 1, access to the shafts 54 and 55 or othermanually-operated operators can be had only when the top panel 13 ismoved rearwardly.

In order to interlock the operation of the loop feeder switches 28 and29 with the fuse drawer I4, pivoted members 56 and 57 are connected toand pivot conjointly with the shafts 54 and 55. The members 56 and 57are generally sectorshaped and have arcuate slots 58 and 59 that arearranged to receive ends 60 and 61 of connecting members or rods 62 and63 which extend horizontally generally toward each other with theirinner ends 64 and 65 pivotally connected to upper drawer latches 66 and67 as shown more clearly in FIG. 4. The upper drawer latches 66 and 67are pivoted at 68 and 69 on the support structure of the metallichousing and they have latch arms 70 and 71 extending therefrom forlatching engagement with upper latch plates 72 and 73 which extendrearwardly from the fuse drawer panel along opposite sides. Lower latchplates 74 and 75 also extend rearwardly from opposite sides of the fusedrawer panel 15 near its lower end. The upper end lower latch plates72-75 are of similar construction and the lower latch plate 75 is shownin elevation in FIG. 6 where it will be observed it is provided with anotch 77. The other latch plates are provided with similar notches forreceiving the latch arms 70 and 71 in the case of the upper latch plates72 and 73. The upper drawer latches 66 and 67 are generally in the formof bellcranks and have arms .80 and 81 to which ends 82 and 83 ofvertical links or rods 84 and 85 are pivotally connected. The lower endsof the links or rods 84 and 85, indicated at 86 and 87, are pivotallyconnected to lower drawer latches 88 and 89 which, in turn, are pivotedat 90 and 91 on the support structure forming a part of the metallichousing 10. Latch arms 92 and 93 which extend from the lower drawerlatches 88 and 89 are arranged to engage notches in the lower latchplates 74 and 75 as described above and shown in FIG. 6.

As long as the loop feeder switch 29 remains in the closed position,shown in FIG. 3, the pivoted member 57 occupies the position shown byfull lines and the latch arms 71 and 93 engage the respective latchplates 73 and 75 and thus prevent opening movement of the fuse drawer14. When the loop feeder switch 29 is opened, the pivoted member 57 ismoved to the position shown by broken lines with the result that theupper and lower drawer latches 67 and 89 are shifted to the positionsthereof shown by broken lines in FIG. 4. The latch arms 71 and 93 aremoved out of the notches in the respective latch plates 73 and 75 and,insofar as they are concerned, the fuse drawer 14 in unlocked. However,it will be understood that the drawer 14 cannot be opened until theother loop feeder switch 28 is opened and the latch arms 70 and 92 aremoved out of latching engagement with the respective latch plates 72 and74.

For locking the vertically slidable panels 44 and 45 against removaladvantage is taken of their lower intumed flanges 94 and 95 which areshown somewhat diagrammatically in FIG. 4. Lockpins 96 and 97, generallyL-shaped, are endwise slidably mounted in guides 98 and 99 with the endsof the long arms arranged to overlie the upper sides of the lowerintumed flanges 94 and 95 of the panels 44 and 45 as illustrated in FIG.6. The short arms 100 and 101 of the lockpins 96 and 97 extend throughslotted openings one of which is indicated at 103 in lockpin levers 104and 105 that are secured to the ends of a shaft 106 which is pivoted inbearing brackets 107 which are suitably mounted on the support structurewithin the metallic housing 10. For pivoting the shaft 106 to withdrawthe lockpins 96 and 97 from overlying relation to the flanges 94 and 95of the panels 44 and 45 an arm 110 is secured to the shaft 106. As shownmore clearly in FIG. 5 a detent in the form of a pin 111 extendslaterally from the lower part of the fuse drawer 14. When the fusedrawer 14 is opened and moved sufficiently far, the detent or pin 111engages the distal end of the arm 110 and shifts it to the positionshown by broken lines in FIG. 5 or sufficiently far to withdraw thelockpins 96 and 97 from locking engagement with the panels 44 and 45.Since this occurs only when the fuse drawer 14 is moved toward the openposition, the panels 44 and 45 can be removed only when this occurs.When the fuse drawer 14 is closed a second detent in the form of a pin112 engages the opposite side of the arm 110, as shown in FIG. 5, topivot the shaft 106 and thereby the lockpin levers 104 and 105 to returnthe lockpins 96 and 97 to their locking positions. The unlocked positionof the lockpin lever 105 is shown by broken lines in FIG. 6. The shaft106 is held in either operated position by a friction spring 113, FIGS.6 and 7, which is secured at 114 to the support structure within themetallic housing 10. The distal end 115 of the friction spring 113 bearsagainst the shaft 106. Thus it is necessary for one or the other of thedetents or pins 111 or 112 to engage the arm 110 to cause a pivotalmovement of the shaft 106.

It will be noted that, when the fuse drawer 14 is open, the lockpins 96and 97 are withdrawn and the panels 44 and 45 can be removed. Should thefuse drawer 14 be closed without first replacing the panels 44 and 45,the lockpins 96 and 97 are moved to their locking positions onengagement of the arm 110 by the detent or pin 112. Now, if an attemptis made to replace the panels 44 or 45, their lower intumed flanges 94and will engage the upper sides of the lockpins 96 and 97 and it willnot be possible to replace the panels 44 and 45 fully in their closedpositions.

When the fuse drawer 14 is open, it is undesirable that the loop feederswitches 28 and 29 be closed. In order to prevent such closure, detents116 and 117 in the form of extensions of the lockpin levers 104 and arearranged to engage arcuate surfaces 118 and 119 on the lower drawerlatches 88 and 89. FIGS. 6 and 7 show the lower drawer latch 89 and thedetent 117 by broken lines in the positions that they occupy when thefuse drawer 14 is open. By preventing pivotal movement of the lowerdrawer latches 88 and 89 the links or rods 84 and 85 prevent movement ofthe upper drawer latches 66 and 67 and thereby of the connecting membersor rods 62 and 63. As a result the pivoted members 56 and 57 are held intheir open positions and pivotal movement of the tool receiving shafts54 and 55 is prevented. Accordingly operation of the spring operators 52and 53 cannot be effected and the loop feeder switches 28 and 29 cannotbe closed. FIG. 3 shows by broken lines the position of the pivotedmember 57 corresponding to the switch open position. It will beunderstood that the pivoted member 56 occupies a similar position whenthe drawer 14 is open.

In operation, when the loop feeder switches 28 and 29 are closed and thefuse drawer 14 is closed, the upper drawer latches 66 and 67 and thelower drawer latches 88 and 89 hold the fuse drawer 14 against openingmovement. Since the fuse drawer 14 is closed, the lockpins 96 and 97prevent removal of the panels 44 and 45. When both of the loop feederswitches 28 and 29 are opened the upper drawer latches 66 and 67 aremoved out of engagement with the upper latch plates 72 and 73 and, atthe same time, the lower drawer latches 88 and 89 are moved out oflatching engagement with the lower latch plates 74 and 75. Then the fusedrawer 14 can be opened. When it has been opened sufficiently far, thepin or detent 111 engages the arm and pivots the shaft 106 to withdrawthe lockpins 96 and 97 from overlying relation with the lower inturnedflanges 94 and 95 of the panels 44 and 45. Then the panels 44 and 45 canbe removed. With the lockpins 96 and 97 withdrawn, the detents 116 and117 prevent pivotal movement of the lower drawer latches 88 and 89 toprevent pivotal movement of the pivoted members 56 and 57, therebypreventing closure of the loop feeder switches 28 and 29.

Iclaim:

1. An interlocking fuse and switch system comprising:

a support structure,

a fuse drawer slidable horizontally on said support structure,

a fuse carried by said fuse drawer,

a switch having a switch blade pivoted on said support structure to oneside of said drawer,

contact means interconnecting said fuse and said switch blade,

a panel vertically slidable on said support structure alongside of saidfuse drawer, overlying said switch and permitting access thereto whenremoved,

manual means for operating said switch blade between closed and openpositions including a pivoted member having closed and open positionscorresponding to closed and open positions of said switch blade,

fuse drawer locking means connected to said pivoted member for unlockingsaid fuse drawer when said pivoted member is in said open position andlocking it when said pivoted member is in said closed position,

panel locking means preventing removal of said panel, and

means for unlocking said panel locking means when said fuse drawer hasbeen opened to a predetermined position.

2. The interlocking fuse and switch system according to claim 1 whereinmeans prevent movement of said pivoted member to closed position whilesaid fuse drawer is open.

3. The interlocking fuse and switch system according to claim 1 whereinmeans operable in response to closing movement of said fuse drawer locksaid panel in place.

4. The interlocking fuse and switch system, according to claim 1 whereinsaid fuse drawer locking means includes:

a notched latch plate secured to said fuse drawer,

a drawer latch pivoted on said support structure for entering the notchof said latch plate to lock said fuse drawer closed, and

a connecting member between said pivoted member and said drawer latch.

5. The interlocking fuse and switch system according to claim 1 whereinsaid panel locking means includes:

a lockpin endwise movable into and. out of locking engagement with saidpanel, a lockpin lever connected to said lockpin, a shaft pivoted onsaid support structure having said lockpin lever secured thereto, an armsecured to said shaft, and detent means on said fuse drawer for engagingsaid shaft for moving said lockpin between locked and unlocked positionswith respect to said panel. 6. The interlocking fuse and switch systemaccording to claim 5 wherein means on said panel engage said lockpinwhen said fuse drawer is closed with said panel removed and preventmovement of said panel to fully-closed position.

7. The interlocking fuse and switch system according to claim I whereinsaid fuse drawer locking means includes:

a notched latch plate secured to said fuse drawer, a drawer latchpivoted on said support structure for entering the notch in said latchplate to lock said fuse drawer closed, and a connecting member betweensaid pivoted members and said drawer latch, and said panel locking meansincludes: a lockpin endwise movable into and out of overlying relationto a part of said panel,

a lockpin lever connected to said lockpin,

a shaft pivoted on said support structures having said lockpin leversecured thereto, and

detent means on said fuse drawer for engaging said arm, to

pivot said shaft.

8. The interlocking fuse and switch system according to claim 7 whereinsaid fuse drawer locking means includes:

a second notched plate secured to said fuse drawer,

a second drawer latch pivoted on said support structure for entering thenotch in said second latch plate also to lock said fuse drawer closed,and

a link interconnects said pivoted latches, and

a detent on said shaft is arranged to engage said second drawer latchwhile said fuse drawer is open to prevent movement of said pivotedmember to closed position while said fuse drawer is open.

9. An interlocking fuse and switch system comprising:

a support structure,

a drawer slidable horizontally on said support structure intermediateits ends,

a fuse carried by said drawer,

a switch on each side of said drawer each having a switch blade pivotedon said support structure,

contact means interconnecting said fuse and said switch blades,

a panel vertically slidable on said support structure along each side ofsaid drawer, overlying the respective switch and permitting accessthereto when removed,

manual means for operating each switch blade between closed and openpositions each including a pivoted member having closed and openpositions corresponding to closed and open positions of the respectiveswitch blade,

fuse drawer locking means connected to each pivoted member for unlockingsaid fuse drawer when each pivoted member is in the respective openposition and locking it when each pivoted member is in its closedposition,

panel locking means individual to each of saidpanels preventing removalthereof, and

means for unlocking each panel locking means when said fuse drawer hasbeen opened to a predetermined position.

10. The interlocking fuse and switch system according to claim 9 whereinmeans prevent movement of each of said pivoted members to its closedposition while said fuse drawer is open.

11. The interlocking fuse and switch system according to claim 9 whereinmeans operable in response to closing movement of said fuse drawer lockeach of said panels in place.

12. The interlocking fuse and switch system according to claim 9 whereineach fuse drawer locking means includes:

a notched latch plate secured to said fuse drawer,

a drawer latch pivoted on said support structure for entering the notchof said latch plate to lock said fuse drawer closed, and

a connecting member between each pivoted member and the respectivedrawer latch.

13. The interlocking fuse and switch system according to claim 9 whereinsaid panel locking means includes:

a lockpin endwise movable into and out of locking engagement with therespective panel,

a lockpin lever connected to each lockpin,

a shaft pivoted on said support structure having each lockpin leversecured thereto,

an arm secured to said shaft, and

detent means on said fuse drawer for engaging said arm to pivot saidshaft for moving said lockpin between locked and unlocked positions withrespect to said panels.

14. The interlocking fuse and switch system according to claim 13wherein means on each panel engage the respective lockpin when said fusedrawer is closed with either of said panels removed and prevent movementof the respective panel to fully-closed position.

15. The interlocking fuse and switch system according to claim 9 whereineach fuse drawer locking means includes:

a notched latch plate secured to said fuse drawer,

a drawer latch pivoted on said support structure for entering the notchof said latch plate to lock said fuse drawer closed, and

a connecting member between each pivoted member and the respectivedrawer latch, and said panel locking means includes:

a lockpin endwise movable into and out of locking engagement with therespective panel,

I a lockpin lever connected to each lockpin,

a shaft pivoted on said support structure having each lockpin leversecured thereto,

an arm secured to said shaft, and

detent means on said fuse drawer for engaging said arm tov pivot saidshaft for moving said lockpins between locked and unlocked positionswith respect to said panels.

16. The interlocking fuse and switch system according to claim 15wherein each fuse drawer locking means includes:

a second notched plate secured to said fuse drawer,

a second drawer latch pivoted on said support structure for a detent onsaid shaft is arranged to engage said second entering the notch in saidsecond latch plate also to lock drawer latch while said fuse drawer isopen to prevent said fuse drawer closed, and movement of either of saidpivoted members to closed a link interconnects said pivoted latches, andposition while said fuse drawer is open.

1. An interlocking fuse and switch system comprising: a supportstructure, a fuse drawer slidable horizontally on said supportstructure, a fuse carried by said fuse drawer, a switch having a switchblade pivoted on said support structure to one side of said drawer,contact means interconnecting said fuse and said switch blade, a panelvertically slidable on said support structure alongside of said fusedrawer, overlying said switch and permitting access thereto whenremoved, manual means for operating said switch blade between closed andopen positions including a pivoted member having closed and openpositions corresponding to closed and open positions of said switchblade, fuse drawer locking means connected to said pivoted member forunlocking said fuse drawer when said pivoted member is in said openposition and locking it when said pivoted member is in said closedposition, panel locking means preventing removal of said panel, andmeans for unlocking said panel locking means when said fuse drawer hasbeen opened to a predetermined position.
 2. The interlocking fuse andswitch system according to claim 1 wherein means prevent movement ofsaid pivoted member to closed position while said fuse drawer is open.3. The interlocking fuse and switch system according to claim 1 whereinmeans operable in response to closing movement of said fuse drawer locksaid panel in place.
 4. The interlocking fuse and switch systemaccording to claim 1 wherein said fuse drawer locking means includes: anotched latch plate secured to said fuse drawer, a drawer latch pivotedon said support structure for entering the notch of said latch plate tolock said fuse drawer closed, and a connecting member between saidpivoted member and said drawer latch.
 5. The interlocking fuse andswitch system according to claim 1 wherein said panel locking meansincludes: a lockpin endwise movable into and out of locking engagementwith said panel, a lockpin lever connected to said lockpin, a shaftpivoted on said support structure having said lockpin lever securedthereto, an arm secured to said shaft, and detent means on said fusedrawer for engaging said shaft for moving said lockpin between lockedand unlocked positions with respect to said panel.
 6. The interlockingfuse and switch system according to claim 5 wherein means on said panelengage said lockpin when said fuse drawer is closed with said panelremoved and prevent movement of said panel to fully-closed position. 7.The interlocking fuse and switch system according to claim 1 whereinsaid fuse drawer locking means includes: a notched latch plate securedto said fuse drawer, a drawer latch pivoted on said support structurefor entering the notch in said latch plate to lock said fuse drawerclosed, and a connecting member between said pivoted members and saiddrawer latch, and said panel locking means includes: a lockpin endwisemovable into and out of overlying relation to a part of said panel, alockpin lever connected to said lockpin, a shaft pivoted on said supportstructures having said lockpin lever secured thereto, and detent meanson said fuse drawer for engaging said arm to pivot said shaft.
 8. Theinterlocking fuse and switch system according to claim 7 wherein saidfuse drawer locking means includes: a second notched plate secured tosaid fuse drawer, a second drawer latch pivoted on said supportstructure for entering the notch in said second latch plate also to locksaid fuse drawer closed, and a link interconnects said pivoted latches,and a detent on said shaft is arranged to engage said second drawerlatch while said fuse drawer is open to prevent movement of said pivotedmember to closed position while said fuse drawer is open.
 9. Aninterlocking fuse and switch system comprising: a support structure, adrawer slidable horizontally on said support structure intermediate itsends, a fuse carried by said drawer, a switch on each side of saiddrawer each having a switch blade pivoted on said support structure,contact means interconnecting said fuse and said switch blades, a panelvertically slidable on said support structure along each side of saiddrawer, overlying the respective switch and permitting access theretowhen removed, manual means for operating each switch blade betweenclosed and open positions each including a pivoted member having closedand open positions corresponding to closed and open positions of therespective switch blade, fuse drawer locking means connected to eachpivoted member for unlocking said fuse drawer when each pivoted memberis in the respective open position and locking it when each pivotedmember is in its closed position, panel locking means individual to eachof said panels preventing removal thereof, and means for unlocking eachpanel locking means when said fuse drawer has been opened to apredetermined position.
 10. The interlocking fuse and switch systemaccording to claim 9 wherein means prevent movement of each of saidpivoted members to its closed position while said fuse drawer is open.11. The interlocking fuse and switch system according to claim 9 whereinmeans operable in response to closing movement of said fuse drawer lockeach of said panels in place.
 12. The interlocking fuse and switchsystem according to claim 9 wherein each fuse drawer locking meansincludes: a notched latch plate secured to said fuse drawer, a drawerlatch pivoted on said support structure for entering the notch of saidlatch plate to lock said fuse drawer closed, and a connecting memberbetween each pivoted member and the respective drawer latch.
 13. Theinterlocking fuse and switch system according to claim 9 wherein saidpanel locking means includes: a lockpin endwise movable into and out oflocking engagement with the respective panel, a lockpin lever connectedto each lockpin, a shaft pivoted on said support structure having eachlockpin lever secured thereto, an arm secured to said shaft, and detentmeans on said fuse drawer for engaging said arm to pivot said shaft formoving said lockpin between locked and unlocked positions with respectto said panels.
 14. The interlocking fuse and switch system according toclaim 13 wherein means on each panel engage the respective lockpin whensaid fuse drawer is closed with either of said panels removed andprevent movement of the respective panel to fully-closed position. 15.The interlocking fuse and switch system according to claim 9 whereineach fuse drawer locking means includes: a notched latch plate securedto said fuse drawer, a drawer latch pivoted on said support structurefor entering the notch of said latch plate to lock said fuse drawerclosed, and a connecting member between each pivoted member and therespective drawer latcH, and said panel locking means includes: alockpin endwise movable into and out of locking engagement with therespective panel, a lockpin lever connected to each lockpin, a shaftpivoted on said support structure having each lockpin lever securedthereto, an arm secured to said shaft, and detent means on said fusedrawer for engaging said arm to pivot said shaft for moving saidlockpins between locked and unlocked positions with respect to saidpanels.
 16. The interlocking fuse and switch system according to claim15 wherein each fuse drawer locking means includes: a second notchedplate secured to said fuse drawer, a second drawer latch pivoted on saidsupport structure for entering the notch in said second latch plate alsoto lock said fuse drawer closed, and a link interconnects said pivotedlatches, and a detent on said shaft is arranged to engage said seconddrawer latch while said fuse drawer is open to prevent movement ofeither of said pivoted members to closed position while said fuse draweris open.